Abstract

A new concealed weapon detection system able to work in open areas without invading individual privacy is presented. This approach is based on pulse induction technology. The paper describes the use of a uniform magnetic field generator for transmitting Heaviside step pulses that cause eddy currents to flow in any metal object carried by the person. The eddy currents excited in the metal body take the form of an exponentially decaying transient immediately following sudden changes in the exciting magnetic field. This decay curve can be used to obtain a time constant which is highly dependent on the size, shape and material composition of the object. A mathematical model of the new concealed weapon detection system is presented showing how the time constant of different metallic objects can be calculated and potentially used as a signature for weapon detection and identification. Simulation results are presented showing the new system is sensitive to the weapon shape but is insensitive to the weapon orientation and the strength of magnetic flux.